1. Technical Field
The present invention relates to a virtual sound source localization apparatus that localizes virtual sound sources around a listener.
2. Background Art
A virtual surround apparatus is known in which multi-channel audio signals are reproduced from two loudspeakers arranged in front of a listener to localize a plurality of virtual sound sources around the listener, thereby allowing the listener to feel a surround sense (a feeling of encirclement) as if a plurality of loudspeakers are arranged around the listener. In such an apparatus, virtual localization is imparted to the audio signals on the basis of head related transfer functions, but since a strict reproduction condition is applied, an optimum listening position where the listener feels the surround sense is limited. For this reason, if the listener changes a seat from the optimum listening position, the listener may not feel the surround sense. In the known apparatus, it is impossible to change the parameters in accordance with the position of the listener so as for the listener to feel the surround sense.
In order to solve this problem, an apparatus is suggested in which a position detection unit for detecting the position of the listener detects the position of the listener, and a coefficient (correction coefficient) based on the head related transfer functions is selected in accordance with a zone where the listener is located, thereby changing sound image localization (see Patent Document 1). In addition, an apparatus is suggested in which the position of the listener is detected by an impulse sound wave emitted from the loudspeaker and a microphone or a camera to measure a distance between the two loudspeakers and the head (ears) of the listener, and sound image localization is set on the basis of the distance (see Patent Document 2).    [Patent Document 1] JP-A-6-253399    [Patent Document 2] JP-A-2007-28134
In the known apparatus, however, it is necessary to set a plurality of correction coefficients at a certain position of the listener. In addition, a position detection unit, such as a camera or a microphone, for detecting the position of the listener is needed. For this reason, the structure or the operation of the apparatus becomes complicated.
Furthermore, as described above, if the listener changes a seat, he/she may not feel the surround sense. Accordingly, if a wide zone with a correction coefficient is set, the listener may not feel the surround sense at the end of the zone. If a narrow zone with a sound image localization coefficient is set, a plurality of sound image localization coefficients may be needed.